Roller-crushing mill



Y 9, 1969 w. BERZ ROLLER-CRUSHING MILL Filed Dec. 30, 1965 ATTORNEY INVENTOR l bljyag 35/12 United States Patent "ice 3,458,142 ROLLER-CRUSHING MILL Wolfgang Berz, Bayerlandstr. 7, Kochel am See, Germany Filed Dec. 30, 15965, Ser. No. 517,652 Int. Cl. B02c 13/13 US. Cl. 241-1ll3 7 Claims ABSTRACT OF THE DISCLOSURE Pulverizing apparatus for comminuting coal in which a plurality of concentric rings are positioned above a plurality of sets of three rollers. The concentric rings are each disposed over each set of rollers.

An object of the present invention is to provide a ring and roller pulverizer of improved efficiency made possible through increased grinding capacity.

Another object is to provide a pulverizer wherein each of a large number of grinding rolls may be maintained at full grinding pressure even when one or more of the grinding rolls is urged away from its normal position by the material to be pulverized.

This invention is an improvement over the ring and roller pulverizing apparatus disclosed in US. Patent No. 2,944,744 issued July 12, 1960, to Max Berz.

The present invention provides a grinding ring supported and carried by a base or table within a casing. The table is rotatably mounted and drivably connected to a source of rotary power. In the upper surface of the grinding ring is formed an annular recess or track adapted to receive a plurality of pressure rollers, the roller surfaces and the track being provided with complementary contacting surfaces. The rollers are divided into two sets, each roller of one set being located between two rollers of the other set. The rollers of one set are positioned at an acute angle of inclination with respect to the surface of the table between its axis and the annular track while the rollers of the other set are positioned at the same acute angle of inclination but with respect to the surface of the table between the annular track and the exterior edge of the table. To exert a downward pressure on each roller a plurality of compression springs are disposed between two concentric pressure rings, each of which engages one set of rollers, and a single thrust ring to provide a yieldable connection between the pair of pressure rings and the thrust ring. The pressure rings are secured within the casing so as to be fixed against rotation, but at the same time provision for vertical displacement of the pressure rings with respect to the grinding table is necessary to compensate for vertical movement of the rollers as they planetate in the track of the table.

Other features and advantages will become apparent from the following description considered in connection with the accompanying drawings forming a part thereof and in which:

FIGURE 1 is a sectional view, in elevation, of the pulverizer according .to this invention; and

FIGURE 2 is a plan view of the rollers and table including track taken along the line IIII of FIGURE 1 3,458,142 Patented July 29, 1969 and showing at line I-I the scope of the sectional view of FIGURE 1.

Referring to the drawings and more specifically to FIG- URE l, 10 designates a casing having a feed tube 12 extending downwardly along the longitudinal axis thereof. A table 14 is horizontally supported in the bottom portion of casing 10 and in spaced relationship with feed tube 12. Table 14 is rotatably driven about its vertical axis by a suitable means such as a motor 15. A grinding ring 16 is rotatably carried on the upper surface of the table 14. In the upper surface of the grinding ring 16 is formed a concave annular grinding recess or track 17.

Six equally spaced pressure rollers 18 planetate in track 17, only two of which rollers, for purposes of clarity, are shown in FIGURE 1. Each roller 18 has a hub portion 25 to which is press fit, or otherwise suitably secured, a bearing collar 26. Collar 26 is provided with a peripheral groove 27 which engages the complementary shaped surface 28, 29 of pressure rings 30 or 31. The surfaces of the rollers and the track may be of any suitable shape; however, it is preferable to provide a track of part-circular or arcuate cross-section and the surfaces of the rollers are toroidal.

Pressure ring 30 has a plurality of spaced slotted lugs 32 in the outer periphery thereof into which project tongues 33 which are secured to casing 10 and extend inwardly therefrom to prevent rotation of the ring 30 and to guide the latter during vertical movement. Internal pressure ring 31 is provided with slots 34 at spaced intervals along its surface adjacent pressure ring 30. Pressure ring 30 also has similar and corresponding slots 35 in its surface adjacent the inner pressure ring 31. Key members 36 are inserted between slots 34 and 35 in the internal and external pressure rings, respectively, to prevent rotation of internal pressure ring 31 and to guide the internal pressure ring 31 during vertical movement independent of the vertical movement of pressure ring 30 Spaced from and above pressure rings 30 and 31 is a thrust ring 37 which has a pulrality of spaced tongues 38, one of which is shown, extending from its periphery, which tongues project into a plurality of slotted lugs 39 which are mounted on and extend inwardly from casing 10. Lugs 32 with tongues 33, keys 36, and lugs 39 with tongues 38 all cooperate to vertically guide and prevent rotation of pressure rings 30, 31 and thrust ring 37. Interposed between the pressure rings 30, 31 and thrust ring 37 are a plurality of spaced compression springs 60 which maintain the pair of pressure rings 30 and 31 and thrust ring 37 in spaced relationship and provide a downward thrust or biasing force upon each of the rollers 18 through their respective pressure rings 30 and 31.

The thrust ring 37 may be retained in a permanent, stationary position or provision may be made for adjusting the thrust ring upwardly or downwardly to control the crushing force maintained between the rollers and the track. One means for adjusting the thrust ring is described in the above-mentioned US. Patent No. 2,944,744 wherein a plurality of thrust ring hold-down assemblies are provided. Rotation of adjustment nuts on threaded studs extending from the housing 10 to the thrust ring 37 permits the thrust ring to be moved closer to the pressure rings 30 and 31 to increase the compression of springs 60 against the pressure rings or to be moved away from the pressure rings 30 and 31 to lessen the spring compression.

By reason of the position of the pressure rings 30 and 31 with respect to their particular sets of rollers 18, the axis of rotation of each of the rollers is at an angle to a horizontal plane which permits the crushing force or thrust to be exerted upon the rollers in a direction towards the deepest part of the grinding track 17. Since rollers 18 support pressure rings 30 and 31 the crushing force of the rollers includes the combined weight of one of the two pressure rings 30 or 31 in addition to the downward force exerted by compression springs 60. This crushing thrust is increased whenever rollers 18 are forced upwardly by the material coming between the rollers and track surfaces, which upward movement compresses, through either of the pressure rings 30 or 31, springs 60.

Unlike the three pressure rollers shown in the abovementioned Berz Patent No. 2,944,744, which are associated with each other through a race member, the present pressure rollers are retained in place only by the track 17 at the bottom and the pressure rings 30 and 31 at the top. This arrangement necessitates some means to keep the rollers substantially evenly spaced relative to each other. This is accomplished by a wedge block assembly consisting of six wedge blocks 40, each wedge block being situated between adjacent rollers 18. Some play is permitted between the rollers and the wedge blocks. The wedge block 40 are retained in position relative to each other by a spider consisting of six fixed arms 42. To five of the arms are pivotally secured at 44 pivoted arms 46 and the sixth fixed arm rigidly supports another fixed arm 48. A wedge block 40 is slipped on to each of the pivoted arms 46 and the fixed arm 48 and secured in position by a keeper 50. The spider is rotatably supported on a central bearing member 52 which rotates about support shaft 54. Gussets 56 are welded between adjacent fixed arms 52 for increased strength.

In the operation of the roller-crushing mill of the present invention, the table 14 carrying grinding ring 16 is rotated by the motor 15. Material to be pulverized such as coal, cement clinkers or the like, is introduced into the mill through feed tube 12 and falls through thrust ring 37 and pressure rings 30, 31 onto the upper surface of the table 14 and into the track 17. As the grinding ring 16 rotates, rollers 18 planetate about the axis of the table 14 and the pressure exerted on rollers 18 by both the weight of pressure rings 30, 31 and by springs 60 through the pressure rings exert a powerful crushing action on the material to be pulverized lying on track 17. The interior of casing is provided with one or more air inlet ducts 58 (see FIGURE 1) disposed in the lower part of the casing 10. An outlet opening (not shown) is provided at the top of the casing communicating with an exhaust fan (not shown). Air is drawn into the interior of the casing through the inlet duct 58 and upwardly past the peripheral edge of table 14 where it entrains finally ground material and carries the particles upwardly past the outer periphery of rings 30, 31 and 37 to the outlet duct. The rollers 18 while planetating push the wedge blocks 40 causing the spider assembly to rotate about the support shaft 54. Equal spacing between the rollers 18 is assured by the wedge blocks 40 and thus the possibility of the rollers becoming clustered on one portion of the track 17 is avoided.

It is readily apparent from the foregoing description that the present invention makes possible the use of a considerable larger number of crushing rollers than Was previously possible, and thus increase the capacity of the mill. Until the present invention was conceived, only three equally spaced crushing rollers had been considered optimum. Referring to Patent No. 2,944,744 previously mentioned, only three crushing rollers can be equally loaded. If a fourth crushing roller is used, a tilting of the pressure ring caused by a large amount of material under one of the crushing rollers will tend to relieve the pressure on adjacent crushing rollers, thus reducing substantially the efiiciency of the mill. With the present invention, one or more of the rollers can be vertically displaced by material to be ground lying in the track without relieving the pressure applied by the other rollers against the track. Specifically, if one of the rollers is raised, one of the pressure rings (30 or 31) will be raised at a point immediately above it. However, the pressure applied through springs 60 to the other two rollers on which that particular ring rests will not change. Sufiicient yieldability between the component parts is provided to permit substantially increased efficiency in the overall operation of the roller-crushing mill.

The present embodiment of the present invention has been illustrated but it is to be understood that such is merely illustrative and not restrictive, and that variations and modifications may be made therin without departing from the spirit and scope of the invention. Therefore, the present invention should not be limited to the precise details set forth.

What I claim is:

1. Pulverizing apparatus comprising a table mounted for rotation and having a concave annular grinding track thereon, means for rotating said table about a central axis, means for introducing material to be pulverized onto said table and grinding track, a plurality of sets of three rollers and each of the rollers having a peripheral grinding face adapted for contact with the concave surface of said track, a plurality of concentric pressure rings and each of said rings being disposed above each of said sets of rollers, a thrust ring disposed above said pressure rings, and compression spring means disposed between said thrust ring and said pressure rings to exert a biasing force on said rollers, whereby during the operation of said pulverizing apparatus pressure exerted by each of said rollers against said annular grinding track will be maintained substantially constant and uniform.

2. Pulverizing apparatus as claimed in claim 1 wherein there are two sets of three rollers and two concentric pressure rings, each pressure ring engaging one set of said rollers, the rollers of one set being alternately disposed with respect to the rollers of the other set around said annular grinding track, the rollers of one set being disposed at an acute angle with respect to the surface of said table between the axis of rotation and the track, and the rollers in the other set being disposed at an acute angle with respect to the surface of the table between the track and the edge of the table.

3. Pulverizing apparatus as claimed in claim 1 wherein there are two sets of three rollers and two concentric pressure rings, each pressure ring engaging one set of said rollers, the rollers of one set being alternately disposed with respect to the rollers of the other set around said annular grinding track, and the rollers of each set being disposed at equal acute angles with respect to a line parallel to said axis and passing through the center of said track, the rollers of one set being tilted towards said axis and rollers of the other set being tilted away from said axis.

4. Pulverizing apparatus as claimed in claim 1 wherein means are provided for raising and lowering said thrust ring whereby the compression on said springs and the resultant biasing force on said rollers may be varied.

5. Pulverizing apparatus as claimed in claim 1 wherein means are provided for maintaining said rollers substantially evenly spaced about said track, said means comprising spacers located between each of said rollers, and a spider rotatable about said axis said spacers being secured to said spider.

6. Pulverizing apparatus as claimed in claim 5 wherein one of said spacers is rigidly secured to said spider and the remainder of said spacers are pivotally secured thereto.

7. Pulverizing apparatus comprising a concave annular grinding track, means for rotating said track, means for introducing material to be pulverized into said track, a plurality of sets of three rollers and each of the rollers having a peripheral grinding face adapted for contact with the concave surface of said track, a plurality of concentric pressure rings and each of said rings being disposed above each of said sets of rollers, and means for exerting a biasing force on said pressure rings, whereby during the operation of said pulverizing apparatus a substantially constant and uniform pressure will be exerted by each of said rollers against said annular grinding track.

References Cited UNITED STATES PATENTS 2,042,204 5/1936 Barley et al. 241-405 10 ROBERT C. RIORDON, Primary Examiner 

